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-   -   Tyvek ??? Or nothing (http://www.diychatroom.com/f19/tyvek-nothing-140126/)

Ryansoho 04-12-2012 09:26 PM

Tyvek ??? Or nothing
 
Hi all.
In the next few weeks I will be taking down all of my old bricks on my house ( long story) and putting up new ones.

At the same time I will be changing all of my windows.

I'm almost certain that my '72 built house has exterior grade drywall behind the bricks and I live in Canada. Toronto to be exact.

Should I be wrapping my house in Tyvek before the bricks go back up ??

Should I change the drywall for plywood or would I be okay keeping the drywall ??

Thanks

joecaption 04-12-2012 09:39 PM

If it was my house I would remove it all go over the wall with OSB and then the tyvec.
Drywall as almost no shear strenght compaired to real wood.
Would give you a far more solid surface to attach the window flanges to.

jomama45 04-12-2012 09:44 PM

I would never recommend Tyvek directly behind brick, unless you're in an arid region, which you obviously aren't. The lowest cost approach would be to add 30# tar paper over the sheating, lapping adequately & flashing properly at every penetration. Be sure to allow a decent airspace (1" min. here) between the brick & backwall and weeps above grade at the base, as well as air vents at the top.

jklingel 04-13-2012 12:17 AM

I'd skip any OSB and use plywood. OSB and any leak may get ugly.

joecaption 04-13-2012 12:43 AM

I see both of you points.
My thinking is from what I have seen when doing remodeling the walls could not breathe when someone used tar paper instead of Tyvek and the inside of the walls molded up, or the wall studs rotted.
It's common to see tar paper used and most often it worked out fine but if there's high moisture under the home, not enough venting under the home, not enough venting in the roof ect. it can cause a problum.
I do mostly remodeling not new constrution so I often get to see what happens years later.
Not sure what differance it would make if there's a wall leak, both will fail.
Not an agrument just a differance of opion.

jklingel 04-13-2012 12:59 AM

joe: tar paper has a perm rating that is very high, or fairly low. I just copied this from http://www.greenbuildingadvisor.com/...elt-astm-d-266

"Asphalt felt has a permeance of only 5 perms when dry, but a much higher rating of 60 perms when wet. Fans of felt note one of its advantages over housewrap: If water gets behind felt — either due to a flashing leak or condensation from solar-driven moisture — the felt can soak up the liquid water and gradually dry to the exterior." Some of the cats mentioned here (Hollady, Straube, etc) know an H of a lot more than me, and I have come to trust them over the years. Variable permeability was a new concept to me until I read this (and other, similar statements). Membrain is a newer product that allegedly does the same thing; a "smart" vapor retarder. If there is damage w/ asphalt felt on a wall, I would suspect there was an inherent design/build issue that would have caused anything to fail. Felt has been around, and working well, for ions. Just my two cents on the deal. I am sure you see and try to repair some serious disasters! Good luck.

Ryansoho 04-13-2012 06:26 AM

Wow. Thanks.
Alot of info here.

What's about on the exterior drywall issue.

Should I remove it and replace it with plywood, should I put plywood right over it. Or could I just leave it and rebrick ??

jklingel 04-13-2012 12:43 PM

I am not familiar w/ "exterior drywall" but like Joe said, it ain't plywood when it comes to structural strength, if it is in fact gypsum-based.

Michael Thomas 04-13-2012 02:29 PM

I inspect leaking masonry buildings here in Chicago for a living.

IMO, 1) proper detailing at horizontal surfaces and wall penetrations, 2) the creation of an unobstructed and properly ventilated drainage plane and 3) the selection of appropriate masonry materials and their correct installation is *far* more important than the choice between any of the acceptable vapor retarders.

Gary in WA 04-13-2012 06:33 PM

Leave the GypRock be, it is better than wood let-in braces alone, and equal to a steel strap-braced wall. Table 4;http://www.fpl.fs.fed.us/documnts/fplrp/fplrp439.pdf
Taping the joints, panel orientation, and fastener connection all have an influence on its racking strength.

OSB or plywood panels are much better for racking resistance for high seismic areas; http://bct.eco.umass.edu/publication...n-the-outside/

Another option is replace just the minimum (corners, etc.) to resist a 90 mph wind; http://www.awc.org/pdf/WFCM_90-B-Guide.pdf Check with your local AHJ.

I'd go; cc foam board--- h.w.(stucco wrap)/paper (2 layers)---existing GypRock----- no f.g. unless existing---v.b. if required (which would reduce f.b. thickness)---- drywall
F.b. over the HW to prevent air-billowing/construction damages, no OSB, intact drainage plane.
http://www.buildingscience.com/docum...ting-sheathing

Gary

jomama45 04-13-2012 07:08 PM

Quote:

Originally Posted by Michael Thomas (Post 898187)
I inspect leaking masonry buildings here in Chicago for a living.

IMO, 1) proper detailing at horizontal surfaces and wall penetrations, 2) the creation of an unobstructed and properly ventilated drainage plane and 3) the selection of appropriate masonry materials and their correct installation is *far* more important than the choice between any of the acceptable vapor retarders.

All of those things are certainly important, but the evidence is prevailing that solar-driven moisture really is a big problem for today's residential masonry veneers...........


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